What is the treatment for arthropod bites?

Treatment of Arthropod Bites

The treatment of arthropod bites should focus on local wound care, symptomatic relief with antihistamines and topical corticosteroids, and immediate epinephrine administration for anaphylactic reactions. 1

Initial Assessment and Management

Non-Venomous Bites (Common Arthropod Bites)

1. Local Wound Care:

   • Clean the area by washing with soap and water to prevent secondary infection 1
   • Apply ice or cold compresses for 10-15 minutes several times daily to reduce swelling 1
   • Remove stingers (if present) within 10-20 seconds by flicking or scraping with a fingernail, avoiding squeezing the venom sac 1

2. Symptomatic Relief:

   • Topical treatments: Apply topical corticosteroids to alleviate itching and swelling 1
   • Oral medications: Use oral antihistamines for urticaria and pruritus 1
   • Low-potency corticosteroids may not be effective for symptom improvement 2

Venomous Bites/Stings with Systemic Reactions

1. Emergency Treatment for Anaphylaxis:

   • Administer epinephrine immediately for signs of anaphylaxis (difficulty breathing, tongue/throat swelling, lightheadedness, vomiting, disseminated hives) 1, 3
   • Dosage: 0.01 mg/kg (up to 0.3 mg) in children and 0.3-0.5 mg in adults, intramuscularly 1
   • Repeat dosing may be required for persistent symptoms 1

2. Supportive Care:

   • Position patient appropriately
   • Establish IV access
   • Administer oxygen if needed
   • Monitor vital signs 1

Treatment Based on Specific Arthropod Types

Spider Bites

1. Widow Spider (Latrodectus) Bites:

   • Treat with analgesics and benzodiazepines 4
   • Consider antivenom for severe, refractory cases (though not widely available) 4

2. Brown Recluse (Loxosceles) Bites:

   • Provide supportive care
   • Wound care and minor debridement as needed 4
   • Most resolve without aggressive therapy 5

Hymenoptera Stings (Bees, Wasps, Hornets, Fire Ants)

1. Local reactions:

   • Ice application
   • Antihistamines
   • Topical corticosteroids 4

2. Severe reactions:

   • Epinephrine (as described above)
   • Systemic glucocorticoids
   • Antihistamines 4

Scorpion Stings

1. Centruroides species (medically relevant in US):
   • Analgesics
   • Benzodiazepines
   • Supportive care
   • Antivenom in severe cases 4

Secondary Infection Management

If signs of infection develop:

• Consider antibiotic treatment with options including:
  • Cephalexin (250 mg four times daily)
  • Clindamycin (300-400 mg three times daily) for penicillin-allergic patients
  • Amoxicillin-clavulanate (875/125 mg twice daily) 1
• Infected wounds should not be closed 2

Prevention of Future Bites

1. Repellents and Protective Measures:

   • Apply insect repellent containing DEET 20% to 50% or picaridin 20% 4
   • Wear permethrin-impregnated clothing 4
   • Cover exposed skin in high-risk areas 4
   • Remove known nests near home 1
   • Avoid bright clothing and strong scents 1

2. Long-term Management for Those with Previous Reactions:

   • Refer patients with systemic reactions to an allergist-immunologist 1
   • Consider venom immunotherapy (VIT) for those with known allergic reactions 1
   • Prescribe EpiPens for patients with previous systemic reactions 1

Follow-up Care

• Monitor for signs of secondary infection, systemic allergic reactions, and delayed healing 1
• Reevaluate in 48-72 hours if there is no improvement 1
• Ensure tetanus prophylaxis is current 2

Common Pitfalls and Caveats

• Delayed use of epinephrine in anaphylaxis can be ineffective or fatal 1
• Brown recluse spider bites are often overdiagnosed 4
• Tourniquets, suction, ice application, and electrical current are ineffective or potentially harmful for venomous snake bites and should be avoided 2
• Low-potency corticosteroids may not improve symptoms of arthropod bites 2